This invention relates to a metering installation for powder pigments. Powder pigments such as those made of iron oxide, titanium dioxide or chromium oxide are used alone, or in mixed form, for dying a wide range of different materials, for example wood, coatings, foodstuff, concrete articles, roofing tiles, composite blocks, etc. They are usually supplied to the end user, from various manufacturers, as bagged goods of approximately 25 kg or in so-called big bags of 1 t. These powder pigments have thus to be mixed with other materials in specified amounts.
The automatic batchwise weighing and conveying of powder pigments is problematic on account of the pronounced bridge formation in containers and conduits. Powder pigments are thus also frequently converted, with the aid of an organic or inorganic binder, into a granular consistency which has good flowing and metering capability. This additional treatment, however, is complex and renders the product considerably more expensive.
It is an object of the invention is to provide a metering installation which makes it possible to use powder pigments as such, i.e. without further treatment.
Thus, the invention concerns a metering installation for powder pigments, having an arrangement for supplying the powder pigments into a weighing container of a weighing arrangement, it being possible for the weighing container to be emptied into a conveying arrangement which comprises a pneumatic conveying conduit which leads into a consuming unit, if appropriate via an intermediate store, wherein the conveying arrangement has a hopper-like pressure container which can be subjected to the action of compressed air and is provided with a closure at the base and with a laterally curved outlet connector, an injector tube, which can be subjected to the action of compressed air and has lateral exit openings for the compressed air, extending axially in the outlet connector.
Since use is made of a metering installation with a conveying arrangement which has a hopper-like pressure container which can be subjected to the action of compressed air and is provided with a closure at the base and with a laterally curved outlet connector, an injector tube, which can be subjected to the action of compressed air and has lateral exit openings for the compressed air, extending axially into the outlet connector, it is also possible for powder pigment weighed by a weighing arrangement to be conveyed upwards over a relatively large distance.
Further, the invention concerns a hopper-like, closeable container for accommodating powder pigments, having an outer wall and a base provided with an outlet, a flexible inner lining adjacent to said outer wall, an interspace between said outer wall and said lining, and means for subjecting said interspace to the action of compressed air in a pulsating manner.
Additionally, the invention concerns a pneumatic conveying arrangement for powder pigments, having a conveying conduit connected to means for subjecting said conduit to the action of compressed air, wherein a hopper-like pressure container being subjectable to the action of compressed air and provided with a closure at its base and with a laterally curved outlet connector is arranged upstream of the conveying conduit, an injector tube, which can be subjected to the action of compressed air and has lateral exit openings for the compressed air, extending axially into the outlet connector
It is expedient here if the weighing arrangement has a weighing container with a flexible inner lining, it being possible for the interspace between the outer wall of the container and the inner lining to be subjected to the action of compressed air in a pulsating manner. Further embodiments, objects and advantages of the invention can be gathered from the following description and the claims.